subSocket.Topics() is not accessible

[shanduur]

As the NewSub returns interface, and subSocket is not exported, the Topics() function is not accessible.

NewSub:

zmq4/sub.go

Line 16 in 2ae9328

func NewSub(ctx context.Context, opts ...Option) Socket {

Topics:

zmq4/sub.go

Lines 120 to 129 in 2ae9328

	func (sub *subSocket) Topics() []string {
	sub.mu.RLock()
	var topics = make([]string, 0, len(sub.topics))
	for topic := range sub.topics {
	topics = append(topics, topic)
	}
	sub.mu.RUnlock()
	sort.Strings(topics)
	return topics
	}